This invention relates to electric lamps and particularly to a lamp assembly capable of throwing beams of light in either one or two different directions as required. Such a dual purpose lamp assembly lends itself to use as, typically, an integral combination of a fog lamp and a cornering lamp on a motor vehicle. More particularly, the invention concerns improvements in such dual purpose lamp assemblies of the type described and claimed in Miyazawa et al. U.S. Pat. No. 4,663,696.
The dual purpose lamp assembly according to the above referenced U.S. patent comprises a relatively large fixed reflector, a movable reflector of smaller size positioned forwardly of the fixed reflector for pivotal motion about a vertical axis, and a light bulb having a filament disposed at the common focus of the fixed and movable reflectors. The movable reflector pivots between a first position, where it coacts with the fixed reflector for reflecting the light rays from the bulb forwardly of the lamp assembly, and a second position where the movable reflector reflects part of the light rays from the bulb toward either side of the lamp assembly. Thus the lamp assembly functions as fog lamp when the movable reflector is in the first position, providing road illumination forwardly of the motor vehicle. Upon displacement of the movable reflector to the second position, on the other hand, the lamp assembly serves the additional purpose of cornering lamp to supplement the vehicle headlamp system by providing additional illumination in the direction of vehicle turn.
This prior art dual purpose lamp assembly has proved to have certain weaknesses arising from its mechanical construction. First of all, being positioned upstandingly in front of the fixed and movable reflectors, the elongate stem, in particular, of the light bulb inevitably intercepts part of the light rays that have been reflected from the movable reflector. Accordingly, the complete light energy emitted by the bulb has not been utilized for the intended purposes.
Another weakness is the lack of adaptability of the above outlined basic design of the prior art dual purpose lamp assembly for the manufacture of various commercial models having different sizes or shapes of lamp housings. This lack of adaptability also comes from the upstanding arrangement of the light bulb in front of the fixed and movable reflectors. If the vertical dimensions of the fixed and movable reflectors are altered each different commercial model, different means must be employed for mounting the bulb so that its filament may be positioned at the common focus of the two reflectors.
An additional inconvenience manifests itself in connection with the assemblage of the lamp assembly or in changing the used bulb. The inconvenience is again attributed to the upstanding arrangement of the bulb. This arrangement requires that the bulb be mounted in position by being inserted upwardly in and through aligned holes in the bottom flanges of the fixed and movable reflectors.